A recent review of studies sought to review the health effects of solar radiation, sunbeds and vitamin D. The researchers looked at data from different time periods for populations at different latitudes, with the aim at looking at the relative risk for cutaneous malignant melanoma associated with sunbed use, vitamin D and UV effects. They found that increased sunbed use was not associated with melanoma. In fact, the real risk of getting skin cancer from a tanning bed is somewhere less than three-tenths of one percent and the beds can actually provide the human body with an excellent source of vitamin D in the winter months.

Those press releases often point to the World Health Organization, which reports that "use of sunbeds before the age of 35 is associated with a 75% increase in the risk of melanoma” -- a statistic often repeated in news stories about tanning beds. But what does that really mean?

Is it 75 percent greater than an already-high risk, or a tiny one? If you read the FDA’s "Indoor Tanning: The Risks of Ultraviolet Rays,” or a number of other documents from the WHO and skin cancer foundations, you won’t find your actual risk.

But as Ratnayake noted, that study "found that less than three-tenths of 1 percent who tanned frequently developed melanoma while less than two-tenths of 1 percent who didn’t tan developed melanoma.” That’s actually about a 55 percent increase, but when the study was pooled with others, the average was a 75 percent increase. In other words, even if the risk of melanoma was 75 percent greater than two-tenths of one percent, rather than 55 percent greater, it would still be far below one percent.

"Our data refute the only direct evidence that UVA causes melanoma, which is not to say that UVA is harmless," said a study's lead author David Mitchell, Ph.D., professor in M. D. Anderson's Department of Carcinogenesis located at its Science Park -- Research Division in Smithville, Texas. "UVA is just not as dangerous as we thought because it doesn't cause melanoma."

Numerous studies have linked vitamin D levels to a reduction in the risk of certain cancers, including breast cancer, but much debate has focused on the means to boost vitamin D levels -- supplements or sunlight.

The link between vitamin D intake and protection from cancer dates from the 1940s when Frank Apperly demonstrated a link between latitude and deaths from cancer, and suggested that sunlight gave "a relative cancer immunity".

Since then there have been numerous studies suggesting associations between vitamin D and lower risks of certain cancers.

Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.

There is growing evidence that 1,25(OH)2D has anticancer effects, but the discovery that non-kidney cells can also hydroxylate 25(OH)D had profound implications, implying that higher 25(OH)D levels protects against cancer in the local sites.

Many studies have established that people who try to stay bronze with the help of a tanning bed tend to have higher blood levels of vitamin D than those who shun the salon.

Regular appointments at the tanning salon may indeed have health benefits. One study of 156 adults found those who regularly soaked up the artificial rays of a tanning bed had a 90 percent higher average vitamin D concentration in their blood. The tanners, who frequented the salon at least once a week for 6 or more months, also had greater bone density in the hips.

A precursor to vitamin D exists naturally in the skin, and exposure to the sun's ultraviolet (UV) rays touches off a chemical process that creates the usable form of the vitamin. Because vitamin D is needed for proper calcium absorption, the nutrient is vital to bone health. There is also a body of research suggesting vitamin D helps protect against certain cancers and some autoimmune diseases, such as type 1 diabetes and multiple sclerosis.